This invention relates to styrene copolymer compositions having reduced surface gloss, a method of reducing the surface gloss of a styrene composition, composite articles incorporating such compositions, and a process for preparing said composite articles. More particularly, this invention relates to weatherable styrene copolymer compositions, especially acrylonitrile-styrene-acrylate (xe2x80x9cASAxe2x80x9d) compositions, having reduced surface gloss, and to multilayer composites incorporating said compositions. The composites are useful as siding materials for the building and construction industry.
Two phase styrene copolymer resins composed of a resin matrix and an elastomeric or rubber component are known to provide a number of useful properties. Illustrative examples are ASA, olefin-styrene-acrylonitrile (OSA) or acrylonitrile-EPDM-styrene resins (AES), and acrylonitrile-butadiene-styrene (ABS). These resins find use in a variety of applications in the building and construction markets (home and commercial siding, window and door profiles, gutters), in leisure and recreation applications (spas, marine components, outdoor furniture, snowmobile components, recreational vehicles, motor homes, campers, etc) and in the automotive industry (body side moldings, bumpers, interior trim, and mirror housings).
Depending on the particular resin and elastomeric compositions, various performance characteristics are possible. For example, ABS resins generally provide excellent low temperature impact resistance and processability. ASA and AES resins are particularly known for desirable impact strength, processability and weather resistance, that is, good color and property retention after long outdoor exposure. Articles extruded of ABS, AES or ASA generally exhibit a surface gloss falling within the high gloss (90 gloss units at 75xc2x0) range or medium gloss (60 gloss units at 75xc2x0) range.
The prior art has long desired to provide styrene copolymer resins and/or compositions which possess the foregoing advantageous physical and performance characteristics but exhibit a low gloss surface appearance. In particular, it would be advantageous to provide ABS, AES and ASA compositions, especially ASA compositions, having low gloss and desirable performance properties.
Such compositions would be of benefit in the construction industry, especially with respect to the manufacture of siding.
Prior art attempts to provide styrene copolymer compositions having a reduced surface gloss have included the embossing of mold surfaces and the application of a low gloss coating material to the surface of a molded plastic article. These methods failed to provide a sufficient reduction in surface gloss and were disadvantageous with respect to processing, cost and/or performance considerations.
Several other prior art attempts have focused on the addition or modification of a particular rubber or elastomeric component.
U.S. Pat. No. 5,081,193 discloses a low gloss agent for thermoplastic resins comprising a grafted copolymer containing a rubber component, especially a low-cis polybutadiene.
U.S. Pat. No. 5,237,004 discloses thermoplastic polymer compositions having reduced surface gloss due to the presence of polymer particles of from 2 to 15 micrometers and having a particular core/shell structure.
U.S. Pat. No. 5,475,053 discloses molding compositions having a matte surface comprising an impact modified thermoplastic A and a matting agent B. The thermoplastic resin A can be ABS, ASA or the like. Matting agent B is a particular graft copolymer having from 30 to 80 of a particularly specified elastomeric grafting base and from 20 to 70% of a particularly specified graft sheath.
U.S. Pat. No. 4,652,614 discloses moulding materials having a mat surface which are based on neutral and acid graft polymers.
U.S. Pat. No. 4,169,869 discloses ABS compounds having a low gloss or mat finish. The claimed compositions are obtained by including polybutadiene and a copolymer of butadiene and acrylonitrile in ABS.
U.S. Pat. No. 4,668,737 discloses graft polymers having a mat surface. The claimed polymers require from 20 to 0.1 parts by weight of a vinyl-group containing, preferably heterocyclic nitrogen base, from 40 to 99.8 parts by weight of particular vinyl aromatic monomers, from 20 to 0.1 parts by weight of a mono- or di-acid containing a polymerizable double bond and from 0 to 40 parts by weight of acrylonitrile on a particulate rubber having an average particle diameter of from 0.05 to 20.0 micrometers and a glass temperature of less than or equal to 10 degrees C., the total rubber content amounting to between 5 and 80% by weight.
However, the foregoing prior art attempts have generally been characterized by one or more disadvantages, especially with respect to the adequacy of surface gloss reduction, quality of surface appearance, cost considerations, ease of manufacturing, ease of processing, and/or the performance properties of the compositions.
Accordingly, it would be advantageous to provide a method for reducing the surface gloss of styrene copolymer compositions, particularly with respect to molded articles made of such styrene compositions, especially ASA.
It would be desirable to provide styrene copolymer compositions, especially ASA compositions, which exhibit desirable performance properties, a reduction in surface gloss as compared to traditional styrene copolymer compositions, advantageous cost considerations, and ease of manufacturing and/or processing.
It would also be desirable to provide composite structures incorporating such low gloss styrene compositions, especially ASA compositions, which are suitable for use as siding, as well as a method for the manufacture of such composites.
It is an object of this invention to provide styrene copolymer compositions, especially ASA compositions, which exhibit a reduced surface gloss when processed.
It is another object of this invention to provide a method for reducing the surface gloss of commercially available styrene copolymer compositions. In particular, it is an object of this invention to provide a method of reducing the surface gloss of commercially available styrene copolymer compositions, especially ASA compositions, which is advantageous with respect to cost and ease of manufacturing.
Finally, it is an object of the invention to provide a composite incorporating the foregoing low gloss styrene copolymer compositions as an exterior layer and a method of making such composites. In particular, it is an object of the invention to provide low gloss styrene copolymer compositions, especially low gloss ASA compositions, which can be used in the manufacture of low gloss, weatherable exterior siding composite structures and to a method of manufacturing such siding composites.
This invention satisfies the foregoing objects and more by providing a particular low gloss styrene copolymer composition which requires the addition, preferably from 0.1 to 20% by weight of the total composition, of a partially crystalline polymer as mating agent. In one aspect of the invention a polyalkyleneterephthalate, or a mixture of different polyalkyleneterephthalates especially polybutyleneterephthalate or polyethyleneterephthalate are used as matting agent. Instead of a polyalkyleneterephthalate a polyalkylenenaphthalate or a mixture thereof may also be used as matting agent. It is also possible to employ a mixture of different polyalkylenenaphthalates. Among the polyalkylene naphthalates polyethylene naphthalate is preferred. According to another aspect of the invention polyamide, polyamide copolymers or a mixture of different polyamides or polyamide copolymers can be used as matting agent. The low gloss styrene copolymer composition of the invention has a graft copolymer resin (A) which results from polymerizing one or more monomers (A1) selected from the group consisting of (i) aromatic vinyl compounds, (ii) ethylenically unsaturated compounds, and (iii) mixtures thereof, in the presence of an elastomeric rubber (A2) in particulate form. The elastomeric rubber (A2) in particulate form results from polymerizing one or more monomers selected from the group consisting of (i) alkyl acrylates having from 1 to 32, preferably 1 to 8 carbon atoms, (ii) butadiene or isoprene, (iii) olefin compounds (other than ii), (iv) ethylenically unsaturated compounds, (v) aromatic vinyl compounds, (vi) polyfunctional monomers having a crosslinking effect, and (vii) mixtures thereof. The low gloss thermoplastic resin compositions of the invention require from 0.1 to 20% by weight of the matting agent (B), all percents by weight being based on the total weight of the composition.
The invention further provides a method of reducing the surface gloss of a styrene copolymer resin by adding to a styrene copolymer resin (A), from 0.1 to 20% by weight of the matting (B), based on the total weight of the composition, preferably at temperatures from about 20xc2x0 C. below the melting point of (B) to temperatures above the melting point of (B).
Finally, the invention also provides a composite suitable for use as exterior siding for a structure, the composite comprising at least one interior layer (I) comprising a thermoplastic resin, and at least one exterior layer (II) having a low gloss styrene copolymer comprising the foregoing copolymer (A) and from 0.1 to 20% by weight of the matting agent (B), all percents by weight being based on the total weight of the composition, wherein exterior layer (II) is continues and coextensive with interior layer (I).